Spa



FIG. 1 is a front perspective view of a spa showing our new design. The broken line showing is for illustrative purposes only and forms no part of the claimed design;

FIG. 2 is a right and left side perspective view thereof; and

FIG. 3 is a top plan view thereof.

FIG. 4 is an elevation view of both the front and rear sides of the spa illustrated in FIG. 1;

FIG. 5 is a left side elevation view of the spa illustrated in FIG. 1; and,

FIG. 6 is a right side elevation view of the spa illustrated in FIG. 1. 

The ornamental design for a spa, as shown and described. 